A matheuristic for minimization of waiting time for trailers with uncertain arrival times

We present a new loading/unloading trailer scheduling problem for a logistics company. There is a building with several warehouses. Each warehouse stores pallets of different types of products in rooms for loading into trailers. Each warehouse has two gates. One gate is for the trailers, the other one is for two forklifts from the central zone (production line). It produces some products which must be placed in the warehouses according to the no wait rule. We assume that the arrival time for each trailer is uncertain. Our goal is to assign all trailers to warehouses and find a schedule for servicing all the trailers with the maximum stability radius under the total waiting time constraint. For this NP-hard problem, we design a two-stage matheuristic. First, we solve the simplified model using the Gurobi solver. Then, the VNS algorithm is used to return the solution into the feasible region taking into account the detailed information about pallets in each warehouse. We generate some test instances using real data from a Dutch logistics company. Computational results for 6 warehouses, 18 types of products, and 90 trailers are discussed. Tab. 4, illustr. 4, bibliogr. 15.